Predetermined torque release wrench



Y 2,934,985 rnEnErEnMrNEn renown RELEASE` WRENCH Peter .1'. Mutola and .lames W. Westphall, Butialo, N.Y., assiguors to Houdailie Industries, Inc., Buifalo, NSY., a corporation of Michigan Application August 21,` 1958, Serial N 756,328

3 Claims. (Cl. 81-52.4)

This invention relates to torque indicating wrenches and more particularly to a wrench arranged to impart an audible and tactile signal to the operator thereof when the desired torque limit has been reached.

Torque indicating wrenches have, in the past, generally been designed to give a visual indication of the amount of torque being applied. Some wrenches of this type have, however, been designed to also appeal to the senses of touch and hearing but these wrenches have generally been of relatively complex design and have, therefore, been relatively expensive to produce.

Since it has been found in practice that torque indicating wrenches must often be used in positions in which it is impossible to see the Wrench itself or any indicator mechanism thereon, applicants have devised a torque indicating wrench which is arranged to impart an audible and tactile signal to the operator when a desired torque setting has'been reached which is ofrelatively simple design and has a minimal number of moving parts.

Accordingly, it is a principal object of this inventionk to provide a torque indicating wrench which is arranged to impart an audible and tactile signal` to the operator thereof when the desired torque limit has been reached.

It is a further object of this invention to provide a wrench of the type above described wherein the torque indication value may be manually and accurately varied.

It is a still further object of the present invention to provide a torque indicating wrench of the type above described having a minimal number of moving parts wherein the driving parts of the Wrench are arranged to break at the instant the desired torque has been reached.

These and other objects of the invention will become apparent from time to time as the following specification proceeds and with reference to the accompanying drawings, wherein:

Figure 1 is a partially sectioned horizontal view of a device Vconstructed in accordance with the principles of the present invention;

Figure 2 is a vertical sectional view through the Wrench illustrated in Fig. 1 and showing the Wrench in the initial position; and

Figure 3 is a vertical sectional view of the wrench illustrated in Fig. 1 but showing the wrench in the tripped position.

In the embodiment of the invention illustrated in the drawing, there is shown a torque indicating wrench comprising a tubular casing 11 which has a threaded end portion 12 intermediate a circumferentially reduced portion 13 of the casing 11 at one endrof the casing.

A cylindrically shaped adjusting handle 14 is threaded on the inner wall thereof to be threadedly received by the threaded end portion 12 of the tubular casing 11 and has a stem 15 protruding from the end 16 thereof into the interior of the hollow casing 11. A movable reaction block 17 has a shoulder 18 formed intermediate the radially reduced and radially enlarged end portions 19 and 20 thereof which is arranged to abut an inner annular shoulder 21 within the interior of the hollow casing 11.

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A thrust washer 22 is provided as an abutment member for spring 25 and is shown in Fig. 2 as abutting the reaction block 17 which has a threaded central passage 24 formed axially therein. An adjusting lscrew 23 is threadedly received within the central passage 24V and is slotted. as at 23u10 receive a screw driver or the like so that the adjusting screw can be rotated to axially move the thrust washer 22 to vary the compressive force of the spring 25 as will hereinafter be more fully described in detail.`

The spring 25 abuts at its other end portion Aa pressure block 26 which has an4 outwardly extendingclevis 27 formed integrally therewith. A pivot pin 28 is secured through suitable apertures to the clevis 27 and. is positioned at a point below the center axis of the tubular casing 11 for reasons which Will hereinafter Vbecome apparent.

An attachment lever 30 extends within the tubular casing 11 and is pivoted about a pivot pin 31 which extends through the side walls of the casing 11 adjacent the outer open end thereof and has a clevis 32 on the outer end thereof which is arranged to receive a tool such as an open end wrench 33. A pair of securing pins 34 extend through aligned apertures in the clevis 32 and the tool 33 and serve as a means for rigidly connecting the tool to the lever 30. The lever 30 is arranged to have limited rotatable movement about the pivot pin 31 and has a concave cavity 35 formed transversely along the inner end of the lever 30.

A three-lobed cam 36 is arranged to have one of its depressions 37 resting against the pivot pin 28 and is further arranged to have one of its lobes 38 received in the concave hollow 35 of the lever 39. When, of course, the wrench 10 is pulled in a counterclockwise direction,

the parts will normally remain in the position illustrated in Figure 2 until a predetermined torque has been applied, at which time, the force applied by the inner end of lever 30 against the lobe 38 of cam 36 will be suicient to cause compression of spring member 25 to thus trip the cam 36 to the position illustrated in Fig. 3.

Obviously, since the stem 15 abuts the reaction block 17, clockwise rotation of the adjusting handle 14 about the casing 11 will move the stem 15, the reaction block 17, and the thrust washer 22 inwardly within the casing 11 to further compress spring 25 so as to increase the force which must be applied by the lever 30 against cam member 36 to retract the pressure block 26.

It will now become apparent that the adjusting screw 23 has been provided to vary the compressive force of the spring 25 and to thereby increase manufacturing tolerance allowances. The adjusting screw may be turned and moved inwardly in the initial assembly operation before the adjusting handle 14 and stem 15 have been mounted on the end of the tubular casing 11 until the thrust washer 22 abuts the spring 25 and the desired low torque setting is reached. Thereafter, the adjusting handle 14 and stem 15 can be mounted on the casing 11 to provide a means for readily manually adjusting the compressive force of the spring 25. To readjust the low torque setting it is only necessary to remove the adjusting handle 14 and stern 15 and rotate the adjusting screw 23 within the central passage 24.

It will further be noted that a screw 41 is threadedly mounted in a radial aperture 42 in the reaction'block 17 and that the screw 41 protrudes from the block 17 and is arranged to slidably move within a slot 40 in the casing 11 to prevent rotatable movement of the block 17 and to serve as a visual indicator of the position of the block 17 within the casing 11.

It will be apparent from the foregoing description of the device and the detailed drawings therefor that if so desired, the torque adjustment feature of the device may be eliminated and that the outer end of the casing 11 may be used as a handle in order to reduce manufacturing cost to a minimum.

Obviously, when the force applied by the lever 30 to the lobe 38 becomes sufficient to rotate the cam 36 about pivot pin 28 to compress spring member 25, the shock created in thecasing 11 by the movementV of the cam 36 will indicate to the operator that the desired torque value has been achieved. Furthermore, the Vshock loading on the wrench will make a noise which will further indicate to the operator that the desired torque value has been achieved. Thus, applicant has provided a torque indicating wrench which may be adjustable or non-adjustable, which will clearly Vindicate to the operator when the desired torque value has been achieved without requiring the utilization of the visual sense of the operator.

It will herein be understood that this embodiment has `been used for illustrative purposes only and that various modifications and variations of the present invention may be effected without departing from the spirit and scope of the novel concepts thereof.

We claim as our invention: n

1. A torque wrench comprising a housing, a tool engaging lever pivotally mounted Withingsaid housing, a block mounted for axial movement within said housing, resilient means biasing said block toward said lever, a clevis at one end of said block, a reaction pin mounted across said clevis, a concave cavity formed in the inner end of said lever, and a multi-lobed cam freely interposed between said block and said lever having one depression thereof abutting said pin and one lobe thereof movably received within said cavity, said cam being rotatable about said pin upon the application of a certain predetermined torque by said wrench to a workpiece engaged by said lever to pivot said lever with respect to said housing.

2. A torque wrench comprising, a housing, a tool engaging lever pivotally mounted within said housing and extending therefrom, a block mounted for axial movement within said housing, a spring within said housing urging said block toward said lever, a handle threadedly mounted on said housing and arranged for axial movement with respect thereto, a stern rigidly connected to said handle and extending within said housing, a thrust washer abutting one end of said spring and operatively connected to said stem, Va clevis at one end of said block, a reaction pin mounted across said clevis, a concave cavity formed in the inner end of said lever, and a threelobed cam freely interposed between said block and said lever having one depression thereof abutting said pin and one lobe thereof movably received within said cavity, said cam being rotatable about said pin upon the application of a certain predetermined torque by said wrench to a workpiece engaged by said lever to pivot said lever with respect to said housing.

3. A torque applying tool comprising a housing, a tool engaging lever pivotally mounted within said housing, a resilient support within'said housing having a clevis at one end thereof, a reaction pin mounted across said clevis, a multi-lobed cam freely mounted within said Vhousing having one depression thereof seated on said pin and having one lobe thereof engaging the free end of said pivotally mounted lever, said cam being rockable about said pin upon an increase in the relative distance between the adjacent ends of said support and said lever to permit pivotal movement of said lever.

YReferences Cited in the file of this patent UNITED STATES PATENTS 2,365,486 Morris Dec. 19, 1944 2,667,800 Garwood Feb. 2, 1954 2,704,472 Booth Mar. 22, 1955 2,731,865 Woods Ian. 24, 1956 2,732,747 Livermont Jan.v 31, 1956 2,743,638 Woods May 1, 1956 2,789,454 Woods Apr. 23, 1957 2,792,733 Walraven et al. May 21, 1957 

